An article written for Safewise has advice on what to do if you think you are being followed:

What do I do if I think I am being followed?

Keep Calm

Do not slam on the gas if you see something suspicious in your mirror. Slow down to give yourself time to think. Experts suggest driving to a police station or other authority office. If you are on foot, stop to look at a shop window and take stock of your surroundings.

Pay Attention

If you think someone is stalking you, make it a point to be extra observant. Do not play on your phone while taking a stroll or zone out behind the wheel. Make note of people you pass or cars that take the same turns as you do.

Mix Things Up

Try taking a detour if you sense someone is following you, such as turning away from your destination and doubling back, whether you are on foot or in the car. If you are still worried, head to a public place or a safe location like a police station.

Go Where the People Are

Instead of walking home, go into a busy coffee shop or town centre. If you are in your car, drive to a full drive to a full car park where there are plenty of witnesses around. Do not go back to your car alone. Check the car before you get in and keep your doors locked.

Break Out Your Phone

There are plenty of apps with personal safety features that you can download on Android or iOS. Some of these can be used to alert the authorities if you are in trouble so have a look. You can still use your phone even if you do not have access to a personal safety service. Call a friend or family member, tell them where you are, and stay on the phone with them until you feel comfortable.

Call the Police

If you feel you are in immediate danger, do not hesitate to contact the police. Calling 999 or the non-emergency police 101 line are always options, as it is better to be safe than sorry.